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Biomedical subjects

R Boos

Publications and source records attributed to R Boos.

51 records · Page 3Linked to original sources

Actions of GABAergic ligands on brisk ganglion cells in the cat retina.

Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the mammalian retina. We tested the actions of iontophoretically applied GABAergic ligands on the spontaneous and stimulus-evoked activity of retinal ganglion cells recorded extracellularly in the in vivo cat eye. GABA as well as GABAA receptor agonists inhibited all brisk ganglion cell types. This action was antagonized by bicuculline. Bicuculline on its own increased the activity of ON-ganglion cells but suppressed OFF-ganglion cells. This suppression effect was abolished during the blockade of glycinergic transmission by strychnine. The GABAB receptor agonist baclofen inhibited OFF-ganglion cells whereas the activity of ON-ganglion cells was either increased or decreased depending on the stimulus contrast. The antagonists, phaclofen and 2-hydroxy saclofen, produced opposite effects to baclofen and antagonized its action. The present study demonstrates that both GABAA and GABAB receptors modulate the activity of ON- and OFF-ganglion cells in the cat retina.

Animals

[Mediastinal cystic lymphangioma as a cause of hydrops fetalis].

This report is upon a case with fetal hydrops on the base of a paracardiac cystic lymphangioma in the mediastinum. The newborn which had hypoplastic lungs and multiple pneumatothoraces died because of a pulmonary insufficiency. An overview is given about the most common causes of the nonimmune fetal hydrops, and the pathomechanisms are discussed.

Female

[Doppler sonography--effect of fetal position, site of the placenta and measurement site of the fetal aorta].

The influence of fetal position, the site of placenta and the site of measurement in the fetal aorta on doppler-flow parameters was investigated in patients with uncomplicated pregnancies. In 20 cases the S/D-ratio was obtained in three different regions of the descending aorta. Measurements superior the renal vessels showed comparable values (4.1-4.3). No differences were found between signals obtained cranial or caudal of the diaphragma. Measurements at the aortal bifurcation showed significantly increased median values (6.6, p less than 0.05). No differences could be obtained concerning the influence of fetal position or site of placenta on S/D-ratio. All median values of a total of 197 patients were in the range of 4.8. Therefore it may be concluded that the above mentioned parameters do not have significant influence on doppler flow parameters in fetal vessels. However, a proximal site of measurement in the descending aorta fetalis should be reassured.

Aorta

[Twin pregnancies with fetofetal transfusion syndrome].

During an observation period of 10 years 30 cases (11%) of twin transfusion syndrome were observed in a collective of 286 twin pregnancies at the University Women's Clinic Heidelberg. Typical symptoms of a twin transfusion syndrome as polyhydramnios, hydrops fetalis, polyserositis, disparity in fetal growth of the twins and pathological CTGs were examined for their diagnostic and prognostic values. A difference in birth weight of more than 25% was noted in only 28% of cases (range 2-58). A polyhydramnios was diagnosed in 63% of cases, an acute form in 30%. Eight of the nine pregnancies with an acute hydramnios ended in an abortion or intrauterine death up to 28 weeks of gestation. Amniocentesis for reduction of the excessive amount of amniotic fluid had no positive therapeutic effect. Eight of the pregnancies, in which a hydramnios had been detected, were further complicated by a hydrops fetalis (23%). Typical sinusoidal CTGs were registered in only 3 cases. Intrauterine fetal mortality respectively abortion up to 28 weeks of gestation was noted in 6 patients (12/60; 20%). Fetal mortality after 28 weeks of gestation occurred in 9/60 cases (15%). Four infants died more than 7 days post partum (7%). The fetal malformation rate was determined in our collective with 7% (4/60 fetuses). No chromosomal abnormalities were observed. The data collected show the prognostic relevance of the parameters analysed and reveal the cases in which a therapy might be effective. Ultrasonographic scanning of fetal activity or doppler flow measurements are further diagnostic procedures that can be employed in surveillance of risk pregnancies with twin transfusion syndrome. Also umbilical cord puncturing under direct ultrasonographic monitoring is of certain diagnostic and therapeutic value.

Cardiotocography

[Prune belly syndrome. Prenatal diagnosis and obstetric procedure].

With an incidence of between 1 in 30,000 and 1 in 50,000 births, prune-belly syndrome (PBS) is a rare malformation syndrome. The phenotypical and pathoanatomic changes range from discrete expression to very severe malformation complexes with extremely poor prognosis. Malformations of the kidneys and the efferent urinary tract are common. In such cases, oligohydramnios often develops early in such fetuses, followed by Potter's sequence. This syndrome can generally be diagnosed by timely ultrasound investigations, i.e., before the end of the first half of pregnancy. Striking features in the fetus are often oligohydramnios and a greatly dilated urinary bladder, more rarely multicystic-dysplastic kidneys and other malformations of the urogenital tract. Diagnostic possibilities and obstetric procedure are described on the basis of ten cases seen between January 1984 and July 1987 at Heidelberg University Gynecological Clinic.

Abdominal Muscles

[Prenatal diagnosis of thanatophoric dwarfism with cloverleaf skull].

Thanatophoric dwarfism is a rare condition occurring in 1 in 100,000 births. To date, only 2 cases have been reported on in which this condition was diagnosed prenatally before the 24th week of pregnancy post menstruationem. The majority of cases reported so far were born by cesarean section. This condition can be diagnosed early by measurement of the fetal diaphyseal bones and accompanying specific diagnostic measures to establish the possible presence of malformations. The pregnancy can then be terminated if need be, and unnecessary interventions thus avoided.

Abortion, Eugenic

[Fetofetal transfusion syndrome in twin pregnancy with prune belly syndrome].

The authors report on a twin pregnancy with one phenotypically normal twin and one with Prune-Belly-syndrome. Since a severe urethral obstruction-malformation complex was apparent, a premature vaginal delivery was aimed for. A pathologic CTG of the healthy twin, with silent and sinusoidal graph pattern, rendered a primary cesarean section necessary in the 36th + 0 week of pregnancy. The cause was established as a fetofetal transfusion syndrome with severe anemia of the phenotypically normal newborn. Following appropriate blood transfusion the subsequent development of this child was free of complications. The child with Prune-Belly-syndrome died on the second day of life.

Adult

[Controlled acoustic and photic stimulation of the fetus in the last pregnancy trimester].

The aim of the study communicated here was to check any fetal reactions occurring after external stimulation (light-optic and acoustic stimuli), depending on fetal behavioral status. The group studied (acoustic/light stimulation) comprised 85 patients with normal course of pregnancy at term (37th to 42nd week of gestation). They were compared with a control group of nonstimulated patients (n = 26), also with normal course of pregnancy and corresponding gestational age. Fetal heart frequencies and an external tokogram were recorded synchronously with the fetal respiration, body, limb and eye movements registered simultaneously by two independent observers and the fetal behavioral statuses were defined (Nijhuis, Prechtl et al. 1982; Boos and Schmidt 1984; van Vliet et al. 1985). The stimulation methods used were as follows: 1. Single-frequency pure tone (2 kHz, 120 dB, 5 sec) 2. Sawtooth-modulated pure tone (0.5-2.0 kHz, modulation frequency 10 Hz, 120 dB, 5 sec) 3. Low-frequency, sawtooth-modulated pure tone (with vibration effect), (0.1-0.3 kHz, modulation frequency 10 Hz, 120 dB, 5 sec) 4. Light stimulation: electronic photographic flash, luminous intensity 25 X 10(6) Lux/10(-3) sec, 8 flash sequences in 10 sec, distance from maternal abdomen 20 cm. In order to rule out purely coincidental changes in fetal attitude, both genuine and "sham" stimulations were performed in randomized sequence, in the latter case without any acoustic or light-optic signals. No differences in fetal reactions were found with the three different acoustic stimulation methods.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Stimulation

[Breech childbirth--obstetrical and antepartum ultrasonography findings].

The clinical and sonographic findings in 662 cases with birth from breech presentation were compared with the obstetric and sonographic data of a control group (births from vertex presentation). There were significantly more primiparae aged over 30 (16%) in the breech birth group investigated than in the control group (p less than 0.001). Vaginal bleeding and/or premature labor were found more frequently in gravidae with breech presentation than in those with vertex presentation (p less than 0.001). Also, premature births occurred significantly more frequently (22%) in the former group than in the latter (9%; p less than 0.001). Furthermore, the proportion of newborns weighing less than 2500 g was higher in the breech presentation group (20%) than in the vertex presentation group (only 5%; p less than 0.001). In addition, newborns with growth retardation, with a weight percentile less than 5 were significantly more common in breech (6%) than in vertex presentation (2.8%; p less than 0.001). Uterine anomalies (in 5.5%) were more common in breech presentation cases than in the control group (0.0%; p less than 0.001). Oligohydramnios was diagnosed by sonography in 20% of the cases with breech presentation, but only in 6% of births from a vertex presentation (p less than 0.001). A pathologic placental location (placenta previa) was found more frequently (3.5%) in cases with breech presentation than in the control group (1.1%; p less than 0.01). Pathologic fetal movement was sonographically observed in 7% of the cases with breech presentation, though only in 1.6% of cases with vertex presentation (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult

[Prenatal diagnosis of severe neural tube defect in negative biochemical findings].

With reference to a case of occipital encephalocele associated with iniencephaly diagnosed by ultrasonography in the 20th week of pregnancy, the diagnostic problems of craniospinal defects, factors influencing prognosis and clinical consequences are described. Even when results of biochemical tests are negative, minute neural canal defects can be diagnosed early by ultrasonography. In the authors' opinion an ultrasonographic diagnosis of encephalocele represents an indication for termination of pregnancy, in view of the poor prognosis.

Abnormalities, Multiple

[Fetal arrhythmia].

Our present knowledge of fetal arrhythmias is described with reference to the literature and to the authors' personal experience. Most types of arrhythmia are harmless. Fetal tachyarrhythmias are of clinical importance, because of the danger of fetal cardiac insufficiency, and atrioventricular blocks because they are closely associated with infantile heart defects and maternal collagen disease. Problems of diagnosis and management are discussed.

Arrhythmias, Cardiac